176 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.37. 



TURBO (PRISOGASTER) NIGER Wood. 



Turbo niger Wood, Index Test., suppl., 1828, pi. 6, No. 1. — Sowerby, Gen. 



Shells, fascic. 37, 1832, Tur^o, fig. 7.— Gray, in Beechey's Voy., Zool., 1839, 



p. 143, pi. 36, fig. 1. 



From rocks at west end of Callao water front; from tidal pool on shingle beach at 



La Punta, Callao; dredged in 2 J fathoms on the northeast side of San Lorenzo Island; 



and common on the rocks along shore at the Chincha Islands. 



Distribution. — From the Straits of Magellan northward to Pacas- 

 mayo, Peru. 



Shell small, turbinate, smooth or spirally striated (especially in 

 southern specimens), black, with a white aperture and smooth nearly 

 hemispherical w^hite shelly operculum; base imperforate, interior of 

 aperture pearly; diameter about 20 mm. 



TEGULA ATRA Lesson. 

 Plate 24, fig. 4. 

 Trochus (iter Lesson, Voy. Coq., 1830, p. 344, pi. 16, fig. 2. 

 With the last species. 



Distribution. — From the Straits of Magellan northward to Pacas- 

 mayo, Peru. 



Shell imperforate, conical, more or less depressed; heavy, solid, 

 lusterless black; with about six moderately convex, nearly smooth 

 whorls ; suture impressefl ; last whorl obtusely rounded at the periph- 

 ery, base flattish, concave in the center, eroded and light purple in 

 front of the aperture ; outer lip with a black' margin, pearly w ithin ; 

 a white callus, bearing a spiral rib and somewhat excavated, in the 

 umbilical region; an obscure tubercle at the end of the pillar. Oper- 

 culum horny, multispiral; diameter of shell about 40 mm. 



This is the largest of the black trochoid species for which the coast 

 is noted. 



TEGULA PATAGONICA Orbigny. 



Trochus patagonicus Orbigny, Voy. Am. Mer., vol. 5, 1840, p. ^08, pi. 55, figs. 

 1-4. — Philippi, Conch. Cabinet, 2d ed., Trochus, p. 225, pi. 34, fig. 12. 

 Taken on the shore rocks at Lobos de Afuera Island. 



Distribution. — San Bias, Patagonia, northward to the Lobos 

 Islands, Peru. 



Shell orbiculate conic, thick, umbilicate, axially granulose-sulcate, 

 uniform brownish or purplish, spire obtuse ; wdiorls five, subcarinate ; 

 sutures excavated, aperture rounded, columella bidentate; diameter 

 about 14 mm. 



TEGULA TRIDENTATA Potiez and Michaud. 



Trochus tridentatus Potiez and Michaud, Gal. de Douai, vol. 1, 1838, p. 321, 

 pi. 29, figs. 16-17.— KiENER, Icon., Trochus, pi. 57, fig. 2. 

 Dredged in Sechura Bay, in 5 fathoms, also taken on the rocks in various places 

 about the harbor of Callao. 



Distribution. — From Talcahuano, Chile, northward to Sechura 

 Bay, Peru. 



